20
S. Takaichi
More than 800 structurally defined carotenoids have been defined in organisms
including land plants, algae, bacteria (including cyanobacteria and photosynthetic
bacteria), archaea, fungus, and animals (Britton et al. 2004). Apart from animals,
these organisms can synthesize many kinds of carotenoids using diverse carotenogenesis pathways. These carotenoids and their pathways can be used as chemotaxonomic markers (Rowan 1989; Bjørnland and Liaaen-Jensen 1989; Liaaen-Jensen
1990; Mackey et al. 1996; Jeffrey and Vesk 1997; Takaichi 2011). In addition, characteristics of the enzymes and genes involved in carotenogenesis have been investigated. Some of the genes show high base sequence similarity from bacteria to
land plants, but others have low similarity. Although some homologous genes have
been proposed (Frommolt et al. 2008; Bertrand 2010), carotenogenesis enzymes and
genes, especially algae-specific ones, have not yet been identified. Takaichi (2011)
summarized “Carotenoids in Algae” around 10 years ago, and this review offers a
revised and updated version of the work.
In this review, the term algae refer to oxygenic phototrophs found in both sea and
fresh water habitats. The group includes the cyanobacteria but excluding land plants.
The distribution of carotenoids, carotenogenesis enzymes, and pathways are summarized. Furthermore, some procedures for the general identification of carotenoids are
outlined as, recently, the identification of carotenoids as reported in some reports has
been inadequate.
2.2 Distribution of Carotenoids
Many different carotenoids are found in algal species. The structures of some of
the important carotenoids in phototrophic microalgae are illustrated in Fig. 2.1.
Among them, approximately 30 types exhibit possible photosynthetic functions,
and others may be intermediates of carotenogenesis or accumulated carotenoids.
Some carotenoids are found only in certain algal divisions or classes; therefore,
these carotenoids and also chlorophylls can be used as chemotaxonomic markers.
Their distribution in algae is summarized in Table 2.1 (Rowan 1989; Bjørnland and
Liaaen-Jensen 1989; Liaaen-Jensen 1990; Mackey et al. 1996; Jeffrey and Vesk 1997;
Takaichi 2011).
Carotenoids contain some unique functional groups. The allene group (C=C=C)
is a unique structure in natural compounds and is found mainly in carotenoids
(Dembitsky and Maoka 2007) including fucoxanthin in brown algae and diatoms, 19
-
acyloxyfucoxanthin in Haptophyta and Dinophyta, peridinin in dinoflagellates, and
9
-cis neoxanthin in green algae and land plants. The acetylene group (C≡C) is also
a unique structure, and acetylenic carotenoids are found only in algae as part of the
composition of alloxanthin, crocoxanthin, and monadoxanthin in Cryptophyta, and
diadinoxanthin and diatoxanthin in Heterokontophyta, Haptophyta, Dinophyta, and
Euglenophyta. The acetylated carotenoids, (C–O–CO–CH 3 ) such as fucoxanthin,
peridinin, and dinoxanthin, are also mainly found in algae including Heterokontophyta, Haptophyta, and Dinophyta. These carotenoids are specific to certain
S. Takaichi
More than 800 structurally defined carotenoids have been defined in organisms
including land plants, algae, bacteria (including cyanobacteria and photosynthetic
bacteria), archaea, fungus, and animals (Britton et al. 2004). Apart from animals,
these organisms can synthesize many kinds of carotenoids using diverse carotenogenesis pathways. These carotenoids and their pathways can be used as chemotaxonomic markers (Rowan 1989; Bjørnland and Liaaen-Jensen 1989; Liaaen-Jensen
1990; Mackey et al. 1996; Jeffrey and Vesk 1997; Takaichi 2011). In addition, characteristics of the enzymes and genes involved in carotenogenesis have been investigated. Some of the genes show high base sequence similarity from bacteria to
land plants, but others have low similarity. Although some homologous genes have
been proposed (Frommolt et al. 2008; Bertrand 2010), carotenogenesis enzymes and
genes, especially algae-specific ones, have not yet been identified. Takaichi (2011)
summarized “Carotenoids in Algae” around 10 years ago, and this review offers a
revised and updated version of the work.
In this review, the term algae refer to oxygenic phototrophs found in both sea and
fresh water habitats. The group includes the cyanobacteria but excluding land plants.
The distribution of carotenoids, carotenogenesis enzymes, and pathways are summarized. Furthermore, some procedures for the general identification of carotenoids are
outlined as, recently, the identification of carotenoids as reported in some reports has
been inadequate.
2.2 Distribution of Carotenoids
Many different carotenoids are found in algal species. The structures of some of
the important carotenoids in phototrophic microalgae are illustrated in Fig. 2.1.
Among them, approximately 30 types exhibit possible photosynthetic functions,
and others may be intermediates of carotenogenesis or accumulated carotenoids.
Some carotenoids are found only in certain algal divisions or classes; therefore,
these carotenoids and also chlorophylls can be used as chemotaxonomic markers.
Their distribution in algae is summarized in Table 2.1 (Rowan 1989; Bjørnland and
Liaaen-Jensen 1989; Liaaen-Jensen 1990; Mackey et al. 1996; Jeffrey and Vesk 1997;
Takaichi 2011).
Carotenoids contain some unique functional groups. The allene group (C=C=C)
is a unique structure in natural compounds and is found mainly in carotenoids
(Dembitsky and Maoka 2007) including fucoxanthin in brown algae and diatoms, 19
-
acyloxyfucoxanthin in Haptophyta and Dinophyta, peridinin in dinoflagellates, and
9
-cis neoxanthin in green algae and land plants. The acetylene group (C≡C) is also
a unique structure, and acetylenic carotenoids are found only in algae as part of the
composition of alloxanthin, crocoxanthin, and monadoxanthin in Cryptophyta, and
diadinoxanthin and diatoxanthin in Heterokontophyta, Haptophyta, Dinophyta, and
Euglenophyta. The acetylated carotenoids, (C–O–CO–CH 3 ) such as fucoxanthin,
peridinin, and dinoxanthin, are also mainly found in algae including Heterokontophyta, Haptophyta, and Dinophyta. These carotenoids are specific to certain